Game of Thrones has a reputation as being more grounded than other fantasy works. Yes, there are dragons and ice zombies and the occasional wizard, but for the most part, the show presents a world where pragmatism rules and fairy tale endings go to die. In part, this realism may stem from the fact that George R. R. Martin draws heavily on history for his stories.

Several of the series’ most shocking and outlandish events have their roots in reality. Rather than retell a particular historical story in a fantasy setting, Martin tends to take bits and pieces from some of the most fascinating time periods and cultures, creating a unique milieu. Even so, there are some clear sources of inspiration, particularly from the roots of British history. Truth may not be stranger than fiction here but it comes pretty close, and some of these stories seem almost too wild to be true — but they are.

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Spoiler Alert! This article touches on events and details from Game of Thrones. Anything up through the end of season five may be discussed, so if you are not caught up, read on at your own peril.

At five seasons and counting, Game of Thrones’ sprawling story of treachery and warfare may seem endless and complex to modern audiences, but it’s still brief compared to its biggest historical parallel, the Wars of the Roses. A series of conflicts fought over the course of 30 years, the Wars of the Roses centered on two noble houses, the Lancasters and the Yorks, fighting for the English throne. If those names seem familiar to GoT fans, it’s because they’re pretty clear inspirations for the Lannisters and the Starks, the two biggest families at the center of the series. The name War of the Roses stems from the now iconic symbols of each house: a red rose for Lancaster, a white rose for York, thought the importance of these symbols is exaggerated by later writers such as Shakespeare.

Martin may have used the Wars of the Roses as a launching point for the War of the Five Kings, but their are some key differences. His tale establishes fairly clear moral distinctions, with the Lannisters being ruthless, pragmatic aristocrats and the Starks noble rebels. No easy distinction exists between the Lancasters and Yorks; both factions wanted the throne of England, and were willing to engage in all manner of scheming and slaughter to win it. Still, there are some common themes that run through both conflicts, chiefly the issue of whether power should pass through inheritance or conquest.

As in the show, claims to the English throne arose due to usurpation and issues of succession. At one point, England was ruled by the Plantagenets. In 1377, the Plantagenet king Edward III died, a year after the passing of his eldest son Edward, the Black Prince. Normally the crown would pass to the eldest son, but since he was dead, his own son, Richard II, inherited it. This angered Edward III’s other three sons, including John of Gaunt (the first Duke of Lancaster) and Edmund of Langley (the first Duke of York.) Eventually, Richard II’s Lancaster cousin, Henry of Bolingbroke, deposed him and crowned himself Henry IV.

Just as Robert Baratheon’s usurpation of the Iron Throne led to numerous claims for control of Westeros, Henry IV’s ascension would sow the seeds of war, as the Yorks would later claim that the Lancasters unlawfully took the throne. If this all seems confusing, rest assured, it doesn’t get any simpler; by the end of the wars, at least five men would sit on the throne of England, and many Henrys, Edwards, and Richards would take a turn.